Casimir effect: threshhold distance?

[nomadreid]

In the Casimir effect, there is a distance d between the plates where the effect is observable. Is this a threshhold effect, so that for any non-zero distance \delta, the effect is not observable at d+\delta, or does this effect taper off? What does this depend on?

[Vanadium 50]

It is a strong function of distance: 1/r6 or 1/r8.

[nomadreid]

It is a strong function of distance: 1/r6 or 1/r8.

Interesting. Thank you. I should get more into the math involved.